Na-cellulose IIB

Fig. 2. X-ray fiber diffraction diagrams of (A) Na-cellulose I, (B) Na-cellulose IIB, and (C) Na-cellulose IV. (Fiber axis is vertical).

Na-cellulose IIB. When Na-cellulose I Is allowed to absorb more... 

The threefold helices of cellulose are chiral, l.e., their left-and righthanded conformations are not Identical. It is not yet known whether the structure of Na-cellulose IIB Is characterized by one particular helix handedness, as both conformations are stable and of not very different conformational energy. The x-ray diffraction diagram (cf. Fig. 2B) Is rich In detail and It should be possible to determine the handedness of the Na-cellulose IIB helix from a detailed x-ray refinement. 

As shown by the x-ray diffraction diagrams reproduced In Fig. 2, the Na-celluloses exhibit a relatively high degree of crystallinity and excellent crystalline orientation. In view of this, further delineation of the transformations and the mechanism of mercerlzatlon were attempted through the crystal structure analysis of three of the complexes Na-celluloses I, IIB, and IV. All analyses have now been nearly completed, and a preliminary account of the results Is given below. The detailed descriptions of the crystal structures will be published separately after the completion of the studies. 

Fig. 7. A comparison of the unit cells of celluloses I and II, and Na-celluloses I, IIB, and IV, drawn roughly to scale. Arrows indicate the probable directions of hydrophobic attractions. Filled circles Indicate the positions of Na" " Ions or water molecules. Secondary and hydrogen bonds are shown by dashed lines.

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